A hoop of radius `2 m` weight `100 kg`.It rolls along a horizontal floor so that its centre of mass has a speed of `20 cm s^-1`. How much work has to be done to stop it ?

Explanation

Here, R=2m, M=100 kg
`v=20 cm//s=0.2 m//s`
Total energy of the hoop `=1//2 Mv^(2)+1//2lw^(2)`
`=1//2 Mv^(2)+1//2(MR^(2))w^(2)`
`=1//2 Mv^(2)+1//2 Mv^(2)=Mv^(2)`
Work required to stop the hoop = total energy of the hoop` W=Mv^(2)=100(0.2)^(2)=4 Joule`